Methods and apparatus for selectively modulating azimuthal non-uniformity in a plasma processing system

Abstract

Methods and apparatus for modulating azimuthal non-uniformity in a plasma processing chamber are disclosed. Apparatus includes a plasma processing system having a plasma processing chamber. There is included an RF power supply and a lower electrode configured to receive RF signal from the power supply. There is also included magnet ring disposed off-center relative to a center of the lower electrode, the magnet ring further disposed in one of a first position and a second position, the first position being below the lower electrode, the second position being around an outer periphery of the lower electrode.

Description

BACKGROUND OF THE INVENTION[0001]Plasma has long been employed to process substrates to form electronic devices. For example, plasma enhanced etching has long been employed to process semiconductor wafers into dies in the manufacture of integrated circuits or to process flat panels into flat panel displays for devices such as portable mobile devices, flat screen TVs, computer displays, and the like.[0002]To facilitate discussion, FIG. 1 shows a typical capacitively coupled plasma processing system having an upper electrode 102, a lower electrode 104 on which a wafer 106 may be disposed for processing. Lower electrode 104 is typically disposed inside of the plasma chamber of which chamber wall 108 is shown. The region between upper electrode 102 and lower electrode 104 above wafer 106 is known as a plasma generating region denoted by reference number 110 in the example of FIG. 1. There is typically a plurality of confinement rings 112, which are substantially concentric rings dispose...

AI Technical Summary

Benefits of technology

The patent text discusses the non-symmetry of components within a plasma processing chamber and how it can affect the uniformity of processing results on a wafer. The non-symmetry can be introduced by factors such as chamber construction or processing realities. The technical effect of the patent is to provide a solution to mitigate the non-symmetry and ensure consistent and uniform processing results on the wafer.

Problems solved by technology

However, practical limitations due to chamber construction and other processing realities may introduce non-symmetry into the chamber, which influences the azimuthal uniformity of processing results on wafer 106.

To elaborate, when the chamber components are not symmetric around the center of the chamber (as viewed from the top of the chamber) for example, the non-symmetry of chamber components influences the RF flux lines, the pressure, plasma density, RF delivery current, or RF ground return current such that the azimuthal non-uniformity of the process may result in non-uniform process results on the processed wafer.

The differences in the lengths of the RF ground return paths introduce different inductances along the ground return paths, which also affect the impedances of the ground return paths.

These variations thus create non-symmetry and azimuthal non-uniformity of the process results.

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